In my case I spent two summers building preproduction units down the regular assembly line in the Wentzville plant (I mean, in addition to the other 45 years I've spent launching product).
It was tricky because the front of dash proliferated between gas jobs and diesel, so I was feeding material into two separate lines - and - I had to do it several stations before the vehicle identity was assigned.
So I had to count ahead and predict where my special parts were going to hit.
Add to that the line was relatively slow (around 36 jobs per hour) and there was a lot of starting and stopping. A lot of times you would be aaaalllmooooost there, and then the line would go down (either a breakdown or for an official break) so you had to sit there a wait for a half hour or shift change or whatever to complete what you were going to do. It was enough to make you crazy trying to keep track of where you were.
At any rate - I had a photo of all my special front of dash assemblies lined up on the shop floor, waiting to be fed into the system, and will all my notations, but I think I lost it when I retired.
There are going to be some confused folks in the unlikely event somebody wants to restore one of those G vans.
K